| Tannery sludge as a by-product tannery wastewater treatment, not only contains a lot of water, high concentrations of organic matter, salts and heavy metals, but also contains bacteria and other toxic substances. Sludge is unstable, easily corrupted, stench, and may be dangerous pathogenic microorganisms, parasite eggs provides a breeding ground, if any emissions are not addressed, not only pollute the environment, but also a serious waste of resources. Tannery sludge treatment and disposal has become a major constraint tannery industry development bottleneck. Sludge disposal of sludge stability is an important part of solidification/stabilization is a cheap and feasible as a sludge treatment technology, so this article use of solidification/stabilization technology to its pre-processing.We selected lime,PFA and cinder as the curing agent in the solidification/stabilization process of tannery sludge.The moisture content of tannery sludge was79.60%, pH was8.16,and the volatile organic matter content was about43.20%. Tannery sludge (dry basis) in the total amount of chromium was40541.5mg-kg-1,the Cr concentration in leaching solution of sludge was2.16mg·L-1.Through the heavy metal concentrations in sludge were below the minimum limit value requirement of national standards, but there is still leaching hazards, the moisture content and mechanical properties of the sludge did not reach the standards for sludge enter into landfill sites.Concentrations of heavy metals in leaching solution and mechanical properties of solidified block, as the indexes by single-factor test and L9(34) orthogonal test, get the best curing ratio, and access to primary and secondary test sequence impact of each factor, the chemical and physical properties of the solidified block approach in line with landfill sludge pretreatment standards and reduce costs. At the same time using scanning electron microscopy-energy spectrum analysis (SEM-EDS) of tannery sludge and its solidification micro-structure of the block. Examine effects of curing days on the moisture content and the compressive strength of solidified sludge. To observe the micro-morphology and elemental composition analysis. Explore the tannery sludge solidified block strength reasons for the formation and discuss the stabilization of tannery sludge solidification mechanism.According to single factor and orthogonal experiment shows that, the effectiveness prioritize, which is lime> cinder> curing time> fly ash, when tannery sludge、lime、cinder and PFA ratio was1:0.12:0.08:0.02, curing time was6days, the solidified block have good synergistic solidification effects. The compressive strength of the solidified sludge block reached884KPa, the moisture content of the solidified block was30.20%, the concentration of heavy metals in leaching solution were lower than the national standard, the sludge met with the landfill standards.And curing of the tannery sludge by micro-block study of the structure shown by the best formula for curing agent for curing tannery sludge,the compressive strength and compactness of the solidified block was greatly improved when the curing time changed from6、8、10、15to20days, more pronounced than the pure sludge block without curing. The solidifying agents played a significant role at the later stage. The SEM test also showed that the solidified sludge block exhibited the acicular structure when the curing time was20days when the magnification was5000times.Good compactness of the solidified sludge mainly came from the ettringite, which was generated from the chemical reaction of lime、 active silicate materials (fly ash and cinder) with water, and the longer curing time also played an important role in improving the compressive strength. |
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